diff --git a/ghost/admin/app/components/posts-list/modals/edit-posts-access.js b/ghost/admin/app/components/posts-list/modals/edit-posts-access.js
index e585821802..3cc9b94846 100644
--- a/ghost/admin/app/components/posts-list/modals/edit-posts-access.js
+++ b/ghost/admin/app/components/posts-list/modals/edit-posts-access.js
@@ -1,15 +1,23 @@
 import Component from '@glimmer/component';
+import EmberObject from '@ember/object';
+import ValidationEngine from 'ghost-admin/mixins/validation-engine';
 import {action} from '@ember/object';
 import {inject as service} from '@ember/service';
 import {task} from 'ember-concurrency';
 import {tracked} from '@glimmer/tracking';
 
+const PostValidatorProxy = EmberObject.extend(ValidationEngine, {
+    validationType: 'post',
+    isNew: false // required for our visibility and tiers validations to work
+});
+
 export default class EditPostsAccessModal extends Component {
     @service store;
     @service settings;
 
-    // We createa new post model to use the same validations as the post model
-    @tracked post = this.store.createRecord('post', {});
+    // We use a simulated post model to use the same validations as the post model without
+    // putting any dummy records in the store and needing to force an "isNew: false" state
+    @tracked post = PostValidatorProxy.create();
 
     get selectionList() {
         return this.args.data.selectionList;
@@ -18,29 +26,27 @@ export default class EditPostsAccessModal extends Component {
     @action
     setup() {
         if (this.selectionList.first && this.selectionList.isSingle) {
-            this.post.set('visibility', this.selectionList.first.visibility);
-            this.post.set('tiers', this.selectionList.first.tiers);
+            this.post.visibility = this.selectionList.first.visibility;
+            this.post.tiers = this.selectionList.first.tiers;
         } else {
             // Use default
-            this.post.set('visibility', this.settings.defaultContentVisibility);
-            this.post.set('tiers', this.settings.defaultContentVisibilityTiers.map((tier) => {
+            this.post.visibility = this.settings.defaultContentVisibility;
+            this.post.tiers = this.settings.defaultContentVisibilityTiers.map((tier) => {
                 return {
                     id: tier
                 };
-            }));
+            });
         }
     }
 
     async validate() {
-        // Mark as not new
-        this.post.set('currentState.parentState.isNew', false);
         await this.post.validate({property: 'visibility'});
         await this.post.validate({property: 'tiers'});
     }
 
     @action
     async setVisibility(segment) {
-        this.post.set('tiers', segment);
+        this.post.tiers = segment;
         try {
             await this.validate();
         } catch (e) {
diff --git a/ghost/admin/tests/acceptance/content-test.js b/ghost/admin/tests/acceptance/content-test.js
index 2e486af714..54a3309cda 100644
--- a/ghost/admin/tests/acceptance/content-test.js
+++ b/ghost/admin/tests/acceptance/content-test.js
@@ -1,5 +1,6 @@
 import ctrlOrCmd from 'ghost-admin/utils/ctrl-or-cmd';
 import sinon from 'sinon';
+import windowProxy from 'ghost-admin/utils/window-proxy';
 import {authenticateSession, invalidateSession} from 'ember-simple-auth/test-support';
 import {beforeEach, describe, it} from 'mocha';
 import {blur, click, currentURL, fillIn, find, findAll, triggerEvent, triggerKeyEvent, visit} from '@ember/test-helpers';
@@ -447,8 +448,7 @@ describe('Acceptance: Posts / Pages', function () {
                         expect(JSON.parse(lastRequest.requestBody).bulk.action, 'add tag request action').to.equal('addTag');
                     });
 
-                    // TODO: Skip for now. This causes the member creation test to fail ('New member' text doesn't show... ???).
-                    it.skip('can change access', async function () {
+                    it('can change access', async function () {
                         await visit('/posts');
 
                         // get all posts
@@ -493,6 +493,15 @@ describe('Acceptance: Posts / Pages', function () {
                         let [lastRequest] = this.server.pretender.handledRequests.slice(-1);
                         expect(lastRequest.queryParams.filter, 'change access request id').to.equal(`id:['${publishedPost.id}','${authorPost.id}']`);
                         expect(JSON.parse(lastRequest.requestBody).bulk.action, 'change access request action').to.equal('access');
+
+                        // ensure creating new posts still works
+                        // (we had a bug where newly created records in the store had `isNew: false` set meaning any saves failed
+                        // because Ember Data attempted a PUT with no id)
+                        sinon.stub(windowProxy, 'reload'); // we had a force-reload in place to workaround the bug
+                        await visit('/editor/post');
+                        await fillIn('[data-test-editor-title-input]', 'New post');
+                        await blur('[data-test-editor-title-input]');
+                        expect(this.server.db.posts.length, 'posts count after new post save').to.equal(5);
                     });
 
                     it('can unpublish', async function () {